This invention relates to a process for sugar-coating a solid preparation such as tablet, pill, granule or grain to thereby increase impact strength shelf life thereof.
Conventional sugar-coating liquids used in preparing sugar-coated tablets contain binders such as gelatin or gum arabic so as to increase strength of the sugar-coating layer or to increase bonding strength between an uncoated tablet and the sugar-coating layer.
However these well-known binders have various disadvantages. For example, gelatin, which has been frequently employed, might show considerable changes including browning with the lapse of time to thereby decrease the commercial value of products. It might further insolubilize the sugar-coating layer, thus retarding the disintegration of tablets. These disadvantages are considered to be caused by protein denaturation of gelatin. When gum arabic is employed, the bonding strength between the sugar-coating layer and the uncoated tablet might be insufficient, which often results in cracks in the sugar-coating layer.
In addition to these binders, it has been recently attempted to use other binders such as sodium carboxymethylcellulose, polyvinylpyrrolidone, polyvinyl alcohol, high-molecular polyethylen glycol and .alpha.-starch in sugar-coating. However these binders still have various defects in that the suspension behaviors and viscosity of the obtained sugar-coating liquid are inappropriate for coating or that the bonding strength thereof is insufficient.